Vulcanizing mold



2 Sheets-Sheet 1 June 1927.

28 E. HoPKlNsoN vULoANIzING MOLD Filed April 18, 192.2

June 28, 1927. 1,634,106

E. HoPKlNsQN VULCANIZING MOLD Filed April 18, 1922 2 Sheets-Sheet 2 Patented June 28, 1927,

ERNEST HORKINSON,

PATENT OFFICE.

dr NEW Yonx, N. Y.

VULCANIZING MOLD.

i Application led April 18, A1922. Seriall'o. 555,294.

This invention relates to the manufacture of tires and more particularly to molds for their vulcanization in a serviceable condition and shape.

Tire vulcanizing molds have heretoforeA been made by casting or forging them -in` iron or steel roughl to shape and subsequently machining t em, particularl their cavity faces, to the exact contour esired. The machining operations are quite expensive, laborious and time-consuming, partic-l so 1n fashlonm the .tread deslgn, o

ularl which in most eases is diflicult engraving.

The present invention aims to provide a mold that is somewhat superior to any that has been used heretofore in that it cures the tires better and externally smoother. A furl ther object of the invention is to provide a mold with a' form of lining that may be removed and re-made without any additional material, or a very negligible addition, to

ne by tedious and either duplicate the original and slightly j worn-out shape, or to impart al new contour to the cavity faces of the mold, thus reducing the cost of replacements or changes in shape. Still another object of the invention is to provide a mold that can be made cheaply and rapidly and therefore will not vex and unduly delay manufacturers in changing the form of their product, or in meeting an emergency such as an urgent requirement -for production in excess of the capacity of the mold equipment on hand.

Without intention to limit more than is required by the prior art, the invention may be said to consist in a mold having a lining on its inner or tire .contacting face which is cast in situ and-preferably in a finished or substantiall finished condition to the exact .contour deslred. The mold is made by castlng, forging, or machining, each of its sections out of cast iron, or steel, or other wearresista-nt metal in the form of a ring which has-one of its sides grooved or hollowed out to approximate the outline of a tire that is y to be made, the hollow or groove being made larger however thanthe tire to provide for the reception of a lining.v A matrix, or form, is then preferably made out of steel,

or other suitable material, in replica prefer,

ably of half of' a tire and with the orti'ons which are duplicate ofthe tread design-"- projections or recessesdefined partly at least by separate and removable sections or segments. About the assembled matrix,

which is laid on a pouring-table, the annu-' lar ring or shell is positioned and secured so that molten metal may be poured or forced into a cavity, that is defined between the shelland the matrix, and given the exact configuration it is desired to obtain on the tire engaging face or wall of each sec-A tion of the mold. Then they matrix is removed and a similar procedure is followed in making the other half of the tire Ivulcanizing mold.

A -preferred embodiment of the invention is illustrated in the accompanying drawings in which Fig. 1 is a cross-section ofa mold half being lined with cast metal being set or solidi- 1 lied against a matrix lpr form of suitable configuration.

Fig. 2 isa section through the mold half on the line 2 2, Fig. 1, v

Fig. 3 shows,a completed mold and a tire casing within 4the same as it appears when vulcanized,

Fig. 4 is a perspective of a typical Aform of removable tread segment, and

Fig. 5 is a cross-section at the tread-form'- ing region of a mold', showing a slightly modified construction of the outer shell at the parting between the mold sections.

In Fig. 3 of the drawings a complete vulcanizing mold 1 is shown in cross-section in .cooperative relation with a sealing-ring 2,

consists of an outer shell or wall 7 of iron, y

steel, or other suitable rigid wear-resistant metal, and an inner. wall or lining 8 of any suitable metal that may be cast in a. finished condition in its'position in the mold. White metal containin vtin and `lead may be employed for the lining but I prefer to use an aluminum alloy with about 10% copper, which has a hard structure, congeals and solidiiies with' a' smooth surface that finishes.

the tire better than the old materials, and does not tenaciously cling to the vulcanized or cured casing. Each shell is -hollowed out lll or grooved on one of its sides, as indicated at 9 a little larger than the tire to be cured in the mold and preferably notched or channeled as indicated at 10 and 1 1, to provide for anchorage'of the lining against displacement. Ports or holes `12 are provided through the walls of the annular shell 7 for the passage of molten metal, preferably at spaced intervals, and either through its sides` as shown, or through its outer periphery, as convenient. The lining is cast to the exact shape of the cavit desired and contacts substantially with t e entire exterior o f the tire casing. Preferably, however, the lining terminates immediately above the portions of. the mold which in use engage the beaded margins of the casin these portions of the mold being defined, in the case illustrated,

v'by ribs 13 in each of the two sections, ex-

tending inwardly from and integral with the hard wear-resistant outer wall or shell 7. The ribs 13 are not essential however,

but are 'desirable to protect the edges of the lining and prolong its serviceability. Ribs 14,'see Fig. 5, may be provided to similar advantage at the tread center of thel mold, against lwear there where theV usage is most severe and where the faces of the sections contact and are subjected to pressure in service, these last named ribs in addition serving to secure the lining against displacement and rendering unnecessary, or less necessary the provision of notches or channels 10 and 11 in the outer shell.

The mol'd shown in Fig. 3 and above described in detail, or various modifications of its type, may be manufactured with great ease and dispatch in a manner now to be.

described.

I `first make the outer shell 7 in any suitable manner, as by casting, or forging, or stamping, with or without a rough machining operation in a lathe or mill. The groove 9 is desirably roughened out or blasted clean,

f but those of its faces .which are to engage with the tire casing during a cure, such as the ribs 13 and 14, are accurately machine 1inished.

I also make a matrix, or form, indicated generally at 15,-preferably of steel and hardened to preserve its sharp outlineswhose surface 16 is preferably Aa replica of half of the tire for which it is intended. The matrix may be in one piece, if the cavity s smooth and concave from: -tread to beadyor so shaped that it can be withdrawn without injuring the lining metal. But if the mold is to be provided with indentations or projections to form a superficial design in the tire, I.I preferably form the matrix ,with removable sections 17 and 18, carrying the projection portions of the desi and having suitable draft, as at 19, between their -interengaging faces where necessary. The

drawing shows a mold for vulcan/izing the @seamos tions 23, which are each a replica ofthe rubber blocks 22 in the casing that is to be cured in the mold. The number of projections 23 on a segment may be varied -to meet requirements, it being essential only v4to provide sufficient draft or clearance on all sides so as not to mar the lining 8 in removing the parts of the matrix carryingthe tread design.

About the lmatrix 15, the outer shell 7 is positioned, as shown in Fig. 1, and held or secured to a pouring-table 24 in any suitable manner. The matrix is preferably formed with an annular shoulder 25 corresponding vin shape and size to the margins of thesealing-ring 2, or core, if the tire casing is to be cured on a core. .And theouter shell 7 is machined, or otherwise formed, to inter-fit with the shoulder 25 of the matrix so as to close one edge ofthe cavity between the matrix and the groove 9 in the shell, the other edge of the cavity/ being closed either by the support or table 24, as shown in Fig. 1,.or by-a rib 14 of the outer shell, if the latter has been formed thereon. `llVith the outer shell. and. matrix assembledto4 define a cavity, as described, molten metal is either poured or forced under several hundred pounds pressure through the holes 12 in the sides or 'y outer peripheryof the shell. p

Whent e'metal congealsv or solidifles,`the matrix is removed. If in the construction illustrated in Fig. 1, the annular section 17 of the matrix is lrstwithdrawn by a lateral movement thereof, then'thesegments 18 car-` ryin several of the tread rejections-23 arev tires under internal fluid pressure. But it isv to beunderstood that the same general construction may be employed for molds used to cure tires 'while they are supported on rigid or collapsible cores or to cure solid tires. It is obvious,`of course, that the matrix may be Vvariously sectioned or parted to obtain any desired tread configuration. Provision may be made for first removing the larger part of the matrix from the mold section, When its 5 lining has been` cast in place, by suitably 1ocating the lines of parting or cleavage between it and the set of sections carrying the projections of the tread design, in which case a, plurality of sets of tread segments may be 10 employed and production of the molds in- 5 and reference should be made to the appended claim for an understanding of its scope.

Having thus described my invention, what I claim and desire to protect by Letters Pat-l ent is -A tire vulcanizing mold having a plurality of com lementary sections whose opposed faces are ollowed out to define a molding cavity of the shape of a vulcanized casing in cross-section, eac of said sections consisting of an outer hard metallic shell and an inner lining of cast metal softer than the metal of the shell, the inner and outer edges of the lining. being protected b ribs flush with its Inoldln face and of har metal integral with the she l.

- -Signed at New York city', county of New York, State of New York, this 15th dayof April, 1922.

ERNEST HOPKIN SON. 

